OCR 2010 A2 Biology Unit 2 - Control, Genome and Environment

Okay thanks.

Umm how would you explain how mutations have harmful or beneficial effect? The book just gives a really long example..?

Okay thanks.

Umm how would you explain how mutations have harmful or beneficial effect? The book just gives a really long example..?

And now i believe is the time for me to panic, so much left to learn I think imma do bio the rest of today. Bricking it.

Please...I'm still on frikkin meiosis!

I used a revision guide for most of it and sometimes the textbook. The textbook takes so long hence learning rev guide then checking for things i missed. then i failed jan so ive gotta learn all that again -.-

Has anyone started revising AS again? Our teacher keeps telling us this is MAJORLY synoptic, but our class has yet to start revising AS again. EEeeeeeepp!

wtf ? I have yet to start proper revision for this unit.

Oh boy, your going to have fun

But I Have No Imagination, im finding that the majority listed in the textbook is the same as this rev guide. Theres just some pointlessly long paras which go round the explanation which are not vital. Im reading it and only found a few minor things, such as that chromosomal mutations are somatic mutations and are not passed on, they only really take place in mitosis at interphase. They can happen during meiosis but it will give rise to a new allele and so genetic variation and if they take place in the egg or sperm, the mutated allele will be present in every cell.

Also found out that cystic fibrosis transmembrane regulator protein forms the channel that maintains Cl- and water across the membrane, the mutation causes it to be unable to transport the water and Cl- ions and so it means the cilia are dehyrdated and thus cant shift mucus which means mucus build up + infections.

Wow reading it seemed to work O.O

Yeah true but you're safer using the actual book.
My mums been on my case since yesterday, because all I've been doing is writing notes from the book and not actually taking in what I'm writing. She told me to ditch all the note taking and just basically READ the book.
Like for meiosis as you explained nicely above, read every point and then look at the diagram illustrating the point. There's no need to write everything down. It works aswell, because all I've been doing today is just reading and I remember a whole lot more than I did when just note taking. I suppose once you've read everything through, you can test yourself by writing out..

Yeah i have the same funnily enough, i write out notes which takes like 2/3 weeks for the whole book (even the rev guide is pretty long for that), yet i dont learn it so it seems like a waste.

The way i do it, is either test yourself by saying key points out loud and writing it down. Only problem is now fusing the book and the revguide and i should be neigh on done for this part.
How you getting on?

Yeah, testing yourself out loud is a good method. Ermm I'm on genes and body plans at the moment. The spec says ' explain that the genes that control development of body plans are similar in plants, animals and fungi, with reference to homeobox genes' but the book is pretty crap at explaining it..do you have any clue as to what we're supposed to learn about this homeobox nonsense?

There ya go
http://www.ibymegaupload.com/showthread.php/6146-Bio-Jan-2010

Yeah, rev guide is good for this bit (more than the book anyway).

Basically, homeotic genes are the 'master' control genes for development.
Proteins code for body plans which are used to develop the body and so you can control the development using proteins by affecting rate of transcription.

Homeotic genes are found in homeobox clusters (so u can also call homeotic genes, homeobox genes). These clusters can code for proteins that move furthur along DNA and bind to specific genes which act as transcription factors (i.e. activating the gene causing its expression or repress it so its no longer produced).

In addition to this you have another two types we need to know, maternal effect genes - those that determine the polarity of an embryo (e.g. which part is the head and which is the end/rear) and then segmentation genes - these determine the polarity of each segment which is set out in the body plan (i also think that it works in telling things where to grow in that segment as a result e.g. in drosphilia, they have a few segments, these determines whhich segment limbs and legs grow etc).

I think that should cover it.

Ooh, good explanation, thank you. This is in the how science works bit, so there's a good chance they'll ask something on it?

Maybe, im a bit suspicious that were going to get asked on vitamins, because theres a mention on many pages/spreads about them.

Oh btw, vitamin A (retinol i think?), an excess of this causes activation of some homeotic genes when an embryo is in development and so messes around with the body plan, so its good to avoid this when a woman is pregnant else it can cause birth defects.